1. Field of the Invention
The present invention relates to an atmospheric flow simulation method for reducing a simulation error of wind speed caused due to an influence of different terrain resolutions using a numerical simulation; and, more particularly, to an atmospheric flow simulation method which can compensate the wind speed of the atmospheric flow field using low-resolution terrain data by obtaining a terrain roughness based on a difference in terrain resolutions and using the terrain roughness as a ground surface condition.
2. Description of Related Art
The numerical flow simulation widely used for simulating the atmospheric flow field has been spotlighted as an important scheme for estimation and measurement in various fields such as atmospheric environment, wind engineering, wind power plant station and the like, because it can correctly simulate features of mechanic turbulent flows by complex terrain.
With respect to numerical flow simulation of atmospheric flow field, the important input data are atmospheric field boundary condition as well as terrain data. To acquire the terrain data in Korea, either sampling of a terrain elevation in grid from contour lines in a numerical map of a National Geographical Information Institute or a shuttle radar topography mission SRTM of 90 m resolution Digital Elevation Model DEM from United States Geographical Survey USGS has been usually used. In a special case, 10 m resolution DEM from the Ministry of the Environment or 1 m resolution DEM from the National Geographical Information Institute can be ued as the terrain data.
However, using high-resolution terrain data (or, a fine-resolution terrain data) such as 1 m resolution DEM with respect to a total simulation area is limited because of heavy numerical simulation load. Therefore, while increasing the terrain resolution only for an interested region or a region of high terrain variation upon performing the numerical flow simulation, the low-resolution terrain data (or, a coarse-resolution terrain data) is obtained by an averaging process of the high-resolution terrain data with respect to a grid unit size.
FIG. 1 is a drawing showing a comparison of the wind speeds at height 10 m from surface using 1 m resolution DEM and 100 m resolution DEM respectively.
Referring to FIG. 1, it is shown that the wind speed of the simulation result using 100 m resolution DEM is higher than that of the simulation result using 1 m resolution DEM because the terrain is moderately sloped as a result of an averaging process. This is a consequent because a wind speed profile near the surface depends on the drag of the surface and fluid density, providing that it is under neutral atmosphere condition. it catch an attention that the simulation error in the downstream zone is accumulatively increased due to the averaged terrain elevation. Particularly, there is an inherent danger of including serious error in the simulation result using the low-resolution terrain data since the simulation range can reach several tens km when simulating the numerical atmospheric flow field to select the wind park.
In low-resolution terrain data, terrain variety expressed in the high-resolution terrain data could be neglected so that the surface becomes planed. It would cause an error in simulating the atmospheric flow field near the surface.